About SES & educational expectations: interrelations in the determination of higher education baccalaureate attainment.

Community colleges and four-year colleges provide two differing alternatives to post secondary education. High school seniors face several options upon high school completion: entering the labor market, entering a community college (for a two-year degree or as a step towards a baccalaureate) or attending a four-year institution. Selection into each of these is clearly not a random process, but one related to previous educational experiences, family characteristics and social class, and educational expectations, among others. Attempting to address this issue of self selection, Rouse (1994 & 1995) explicitly posed the question of the democratization versus diversion effects of community colleges. Her work provides evidence of a rational behavior on the part of two-year college students who respond to price and proximity of such institutions (1994), and of the existence of primarily a democratization effect (1994 & 1995). This paper proposes a variation on the work by Rouse (1995) and Leigh and Gill (2003) by inquiring into the effect of SES in relation to students’ educational expectations. It builds on these two models. The underlying hypothesis is that expectations are not independent from SES and therefore examining social class differences and their interaction with educational expectations would support the theory of endogeneity between educational expectations and socioeconomic background. We directly control for expectations and interactions between SES and expectations, as well as considering variations to modeling SES and use alternative estimation methods for bounded probabilities (Logit and Biprobit) and compare these to their approaches. W find the effect of expectations on the probability for middle and middle-high class students’ proved steeper than for the everyone but low SES students. Effect on expected probabilities increasing with SES. These results disappear when estimation methods are improved, using logits and bivariate probit methods, instead of OLS and IVs (explicitly modeling expectations). However, the democratization effect remains significant through all estimations, and strengthens when estimation methods are improved. Out estimates therefore reinforced the findings by Rouse (1995) and Leigh and Gill (2003) of a positive democratization effect that outweighs any diversion effects.higher education; instrumental variables; bivariate probit; expectations; democratization effect; post secondary educational attainment

Endogenous and exogenous constraints in the population changes of wild boar (sus scrofa Linnaeus, 1758)

The population dynamics of wild boar (Sus scrofa) was studied in a time series over 26 years using data from the Regional Hunting Reserve of Somiedo (northern Spain). This population is controlled by a complex negative feedback system that acts with one (main) and two (secondary) years of delay (lags). The primary feedback might be explained by intraspecific competition for food resulting from fluctuations in mast production (acorns and beech), and the secondary feedback might be explained by the influence of weather conditions or the delay of a cohort to reach reproductive status. We used a stochastic model that takes environmental variability into consideration when testing the demographical analysis that’s obtains simulations from real data

How Much Can High-Quality Universal Pre-K Reduce Achievement Gaps?

Many children of color and children from low-income families enter kindergarten without the academic skills they need to succeed. Compared to their white peers, African American and Hispanic children are anywhere from 9 to 10 months behind in math and 7 to 12 months behind in reading when they enter kindergarten. These achievement gaps are concerning: Math and reading abilities at kindergarten entry are powerful predictors of later school success, and children who enter kindergarten already behind are unlikely to catch up. Moreover, in the past 50 years, minimal progress has been made toward reducing these achievement gaps. Ensuring that all children are entering kindergarten with the foundational academic skills they need to succeed is a major priority for researchers, policymakers, and practitioners alike. Early childhood education programs show promise toward this goal. Research suggests that participation in a high-quality early childhood education program can enhance children's development, reduce achievement gaps at kindergarten entry, and even have long-term benefits for children's school trajectories. However, access to high-quality pre-K in the United States remains quite low and highly unequal due to two problems. First, although pre-K attendance has increased in the past two decades, rates of access to early education vary widely as a function of children's socioeconomic backgrounds: African American, Hispanic, and low-income children are less likely to access center-based early childhood education than their white and more affluent peers. Second, the quality of most early education programs -- particularly those attended by low-income children of color -- is not high enough to substantially improve academic readiness. Recognizing the tremendous potential for high-quality preschool to improve children's outcomes, this report considers how a universal publicly funded prekindergarten program in the United States could decrease both disparities in access to early learning and achievement gaps at kindergarten entry. Data from two nationally representative datasets and prior results from evaluations of high-quality universal pre-kindergarten were analyzed to estimate the extent to which a national high-quality universal pre-K, or UPK, program would reduce achievement gaps at kindergarten entry based on children's race/ethnicity and income

optimización da planificación de adquisición de datos LIDAR cara ó modelado 3D de interiores

The main objective of this doctoral thesis is the design, validation and implementation of methodologies that allow the geometric and topological modelling of navigable spaces, whether inside buildings or urban environments, to be integrated into three-dimensional geographic information systems (GIS-3D). The input data of this work will consist mainly of point clouds (which can be classified) acquired by LiDAR systems both indoors and outdoors. In addition, the use of BIM infrastructure models and cadastral maps is proposed depending on their availability. Point clouds provide a large amount of environmental information with high accuracy compared to data offered by other acquisition technologies. However, the lack of data structure and volume requires a great deal of processing effort. For this reason, the first step is to structure the data by dividing the input cloud into simpler entities that facilitate subsequent processes. For this first division, the physical elements present in the cloud will be considered, since they can be walls in the case of interior environments or kerbs in the case of exteriors. In order to generate navigation routes adapted to different mobile agents, the next objective will try to establish a semantic subdivision of space according to the functionalities of space. In the case of internal environments, it is possible to use BIM models to evaluate the results and the use of cadastral maps that support the division of the urban environment. Once the navigable space is divided, the design of topologically coherent navigation networks will be parameterized both geometrically and topologically. For this purpose, several spatial discretization techniques, such as 3D tessellations, will be studied to facilitate the establishment of topological relationships, adjacency, connectivity and inclusion between subspaces. Based on the geometric characterization and the topological relations established in the previous phase, the creation of three-dimensional navigation networks with multimodal support will be addressed and different levels of detail will be considered according to the mobility specifications of each agent and its purpose. Finally, the possibility of integrating the networks generated in a GIS-3D visualization system will be considered. For the correct visualization, the level of detail can be adjusted according to geometry and semantics. Aspects such as the type of user or transport, mobility, rights of access to spaces, etc. They must be considered at all times.El objetivo principal de esta tesis doctoral es el diseño, la validación y la implementación de metodologías que permitan el modelado geométrico y topológico de espacios navegables, ya sea de interiores de edificios o entornos urbanos, para integrarse en sistemas de información geográfica tridimensional (SIG). -3D). Los datos de partida de este trabajo consistirán principalmente en nubes de puntos (que pueden estar clasificados) adquiridas por sistemas LiDAR tanto en interiores como en exteriores. Además, se propone el uso de modelos BIM de infraestructuras y mapas catastrales en función de su disponibilidad. Las nubes de puntos proporcionan una gran cantidad de información del entorno con gran precisión con respecto a los datos ofrecidos por otras tecnologías de adquisición. Sin embargo, la falta de estructura de datos y su volumen requiere un gran esfuerzo de procesamiento. Por este motivo, el primer paso que se debe realizar consiste en estructurar los datos dividiendo la nube de entrada en entidades más simples que facilitan los procesos posteriores. Para esta primera división se considerarán los elementos físicos presentes en la nube, ya que pueden ser paredes en el caso de entornos interiores o bordillos en el caso de los exteriores. Con el propósito de generar rutas de navegación adaptadas a diferentes agentes móviles, el próximo objetivo intentará establecer una subdivisión semántica del espacio de acuerdo con las funcionalidades del espacio. En el caso de entornos internos, es posible utilizar modelos BIM para evaluar los resultados y el uso de mapas catastrales que sirven de apoyo en la división del entorno urbano. Una vez que se divide el espacio navegable, se parametrizará tanto geométrica como topológicamente al diseño de redes de navegación topológicamente coherentes. Para este propósito, se estudiarán varias técnicas de discretización espacial, como las teselaciones 3D, para facilitar el establecimiento de relaciones topológicas, la adyacencia, la conectividad y la inclusión entre subespacios. A partir de la caracterización geométrica y las relaciones topológicas establecidas en la fase anterior, se abordará la creación de redes de navegación tridimensionales con soporte multimodal y se considerarán diversos niveles de detalle según las especificaciones de movilidad de cada agente y su propósito. Finalmente, se contemplará la posibilidad de integrar las redes generadas en un sistema de visualización tridimensional 3D SIG 3D. Para la correcta visualización, el nivel de detalle se puede ajustar en función de la geometría y la semántica. Aspectos como el tipo de usuario o transporte, movilidad, derechos de acceso a espacios, etc. Deben ser considerados en todo momento.O obxectivo principal desta tese doutoral é o deseño, validación e implementación de metodoloxías que permitan o modelado xeométrico e topolóxico de espazos navegables, ben sexa de interiores de edificios ou de entornos urbanos, ca fin de seren integrados en Sistemas de Información Xeográfica tridimensionais (SIX-3D). Os datos de partida deste traballo constarán principalmente de nubes de puntos (que poden estar clasificadas) adquiridas por sistemas LiDAR tanto en interiores como en exteriores. Ademáis plantease o uso de modelos BIM de infraestruturas e mapas catastrais dependendo da súa dispoñibilidade. As nubes de puntos proporcionan unha gran cantidade de información do entorno cunha gran precisión respecto os datos que ofrecen outras tecnoloxías de adquisición. Sen embargo, a falta de estrutura dos datos e a seu volume esixe un amplo esforzo de procesado. Por este motivo o primeiro paso a levar a cabo consiste nunha estruturación dos datos mediante a división da nube de entrada en entidades máis sinxelas que faciliten os procesos posteriores. Para esta primeira división consideraranse elementos físicos presentes na nube como poden ser paredes no caso de entornos interiores ou bordillos no caso de exteriores. Coa finalidade de xerar rutas de navegación adaptadas a distintos axentes móbiles, o seguinte obxectivo tratará de establecer unha subdivisión semántica do espazo de acordo as funcionalidades do espazo. No caso de entornos interiores plantease a posibilidade de empregar modelos BIM para avaliar os resultados e o uso de mapas catastrais que sirvan de apoio na división do entorno urbano. Unha vez divido o espazo navigable parametrizarase tanto xeométricamente como topolóxicamene de cara ao deseño de redes de navegación topolóxicamente coherentes. Para este fin estudaranse varias técnicas de discretización de espazos como como son as teselacións 3D co obxectivo de facilitar establecer relacións topolóxicas, de adxacencia, conectividade e inclusión entre subespazos. A partir da caracterización xeométrica e das relación topolóxicas establecidas na fase previa abordarase a creación de redes de navegación tridimensionais con soporte multi-modal e considerando varios niveis de detalle de acordo as especificacións de mobilidade de cada axente e a súa finalidade. Finalmente comtemplarase a posibilidade de integrar as redes xeradas nun sistema SIX 3D visualización tridimensional. Para a correcta visualización o nivel de detalle poderá axustarse en base a xeometría e a semántica. Aspectos como o tipo de usuario ou transporte, mobilidade, dereitos de acceso a espazos, etc. deberán ser considerados en todo momento